Relationship between initial post-aspiration chest radiograph (CXR) and tracer gas status and the outcome of primary spontaneous pneumothorax
| n | No further intervention | Intercostal drain | Re-aspiration | |
| CXR improved; tracer gas –ve | 27 | 26 (96%) | 0 | 1 (4%) |
| CXR improved; tracer gas +ve | 37 | 19 (51%) | 10 (27%) | 8 (22%) |
| CXR not improved; tracer gas –ve | 2 | 1 (50%) | 1 (50%) | 0 |
| CXR not improved; tracer gas +ve | 14 | 0 | 13 (93%) | 1 (7%) |
| CXR not performed; tracer gas +ve | 4 | 0 | 4 (100%) | 0 |
CXR improved = significant reduction in size of the pneumothorax; CXR not improved = pneumothorax unchanged in size or larger.